In related art horizontal nanosheet (hNS) devices, extension regions of the source and drain electrodes are doped by diffusion from the source and drain electrodes. However, it is difficult to achieve abrupt junctions by diffusion from the source and drain electrodes and there is a tradeoff between the parasitic resistance of the device and the abruptness of the junctions. Additionally, it is difficult to scale with this method because the dopants travel across the width of the internal spacers. Moreover, doping the extension regions from the source and drain electrodes does not self-align the extension regions with the gate stack of the device.
In related art FinFET devices, doped external spacers may be used to dope the extension regions of the source and drain electrodes. However, doping the extension regions by diffusion from external spacers requires the dopants to travel a relatively large distance to reach the middle of the horizontal nanosheet, which results in non-uniform doping across the width of the extension regions. Additionally, in the formation of related art FinFET devices, the materials used as diffusion sources are typically not adequate as spacer material because they are not etch resistant and therefore are not compatible with self-aligned contact (SAC) processes. Accordingly, in the formation of related art FinFET devices, the external spacers used to dope the extension regions are replaced by external spacers having a different, more robust (e.g., etch-resistant) material compatible following the doping of the extension regions with the sacrificial external spacers.